Geoffrey Landis, a scientist at NASA's Glenn Research Center, suggests that Venus might be a good place to look.

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In a recent interview, he suggested building a city in the clouds about 31 miles (50 kilometers) above the surface.

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At that altitude, the atmosphere of Venus is at its most Earth-like. The atmosphere has an air pressure of about one bar and the temperature ranges in the 32-122 degrees Fahrenheit range (0-50 degrees Celsius). You'd need breathing apparatus, but probably not a space suit.

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Landis adds that a city might not be as difficult to build â€” and to keep afloat â€” as you might think.

"Because the atmosphere of Venus is CO2, the gases that we live in all the time, nitrogen and oxygen, would be a lifting gas," Landis said. "On Earth, we know to get something to lift, you need something lighter than air. Well, on Venus, guess what? Our air is lighter than air, or at least lighter than the Venus atmosphere."

There's the idea of having basically a dome, that keeps afloat by the air in the main breathing gas. Such an idea could be modified into corridors and such.

Of course, Hydrogen would be a good lifting gas. Non-flammable (in the Venusian atmosphere, although it may react with the CO2 in an exo?thermic reaction) with a high lifting rate, we could use idea for Earth based flying cities but with a much smaller gas bag.

Might the materials "Wurtzit-Bornitrid" and Lonsdaleite be of interest?

An article under www.wissenschaft.de tells that the first of them is harder than diamond by 18% and the second by 58%. For Venus I suppose it to be of meaning that the first can resist to higher temperatures than the second when exposed to the air - the question remaining if this still is valid in a CO2-atmosphere.

Since they are said to be of interest as layers of space vehicles it seems to me as if they even might resist to higher pressure.

What if prefab platforms were built basically with the same concept as floating in water. A gas sac would remain under a platform with a thick dome. The protection above the platform could be thinner to allow more light through. Balance might be too big an issue to overcome with this design. However, if the platforms were relatively small (maybe an area of 1 kmÂ²?) then they could be locked together in a series. Several high strength balloons could be attached around the edges to maintain some more stability as well.

This would leave a lot of room to scale up the city cheaply until a more permanent structure was in place. Unstable sections could be quickly detached without much loss in structural integrity. Nuclear powered blimps could drag the city places in place of a stability balloon. This design might even make a useful power source as well. The gas located below the platforms would be heated constantly by Venus's atmosphere. Maybe a constant natural wind system would develop depending on how cool the living areas would have to be?

Probably a Hybrid system (with some lift from Hydrogen, most from Air) could work best. In this situation, a platform would be built first which has a Hydrogen bag(s) underneath. This would lift the structure, and allow for bouyuncy corrections. Then the structure would be filled with Air, which would provide the lift for the items inside.

JP has said on these forums that Venus is the location he ultimately intends on implementing his DSS technology once it's more or less mature. My question: all right we have a cloud city in Venus' atmosphere. Now what the hell are we going to do there? Are there useful gasses that can be extracted straight out of the atmosphere? Are we going to seed it with plants to soak up CO2? (floating algae anyone?) It's all well and good to have stuff there but first we need something that makes it worthwhile, as well as more redundancy than you can possibly imagine to make sure we can get out if one of the balloons pops.

those ones are obvious and don't require a city, just a nifty little platform you put there then go chill for a month on.

the real question is what you could do that would require a city. i'm sure there's some stuff that's valid. i for one like the idea of seeding venus' upper atmosphere with greenery (preferably designed to float so it doesn't have to be tethered). then maybe we could do some crazy stuff up there, including eventually lowering the amount of CO2, and simultaneously having the cities slowly sink as the atmosphere becomes more oxygenated and cooler. that's scifi though who knows if it would actually work. but seriously, tropical resorts at venus' poles? i like the sound of that!

Oh, exporting Sulper could be a source of income as well. And Venus is well placed to capture Asteroids, with its thick atmosphere for Aerobraking and no risk of killing people.

I'd like to see Venus with water clouds. That idea isn't so far fetched. A few comets to deliver water, and export the Sulpher. Once that was done, open air Gardens could be built. Humans wouldn't be able to breathe, but plants would. The 4 day 'day' shouldn't pose too much of a problem.

Hybrid Hydrogen/Air airships might be the best option. 1m^3 of Hydrogen on Venus can lift 1.5kg at the 1bar cloudtops. Air can lift about 0.625kg. If the base of the colony had Hydrogen to a depth of one meter on its underside, the actual structure of the colny could be lifted by the Hydrogen, leaving the Air to lift the people, animals, plants, and such. Open air living (well, open air inside the colony), as the climate would be controlled, would be quite nice. The craft could get by with minimal maintainence, so it would be alomost unrecognizable that you were living in a floating colony. Unless you looked out the window. Lightweight houses could be built, to give some privacy.

A rectangulur craft (rounded edges near the top, of course) that is 5m tall, 10m wide, and 20m long, with a 1m Hydrogen base, and a rounded tip adding 5m to the length (making it 25m long) would be able to lift

5*10*20=1000. That can lift 625kg. The base would be 10*20=200, which with Hydrogen to a depth of 1m could lift 300kg. The extra semicircle would add 5^2*pi/2=39m^2. 39*1.5=58.5kg extra lift from the Hydrogen. 39*5*0.625=121.8kg of lift. 625+300+58.5+121.8=1.105 tonnes of lift.

1.105 tonnes should be enough to account for the structure, if it is made out of light materials. The structure could be carried by the 358.5kg of lift provided by the hydrogen, leaving us with 746.8kg of lift for the people and their creatures. This would probably be a roomy but sparse place for a small family farm. Or a park.

Indian scientists have discovered three new species of bacteria in the upper atmosphere.

New Delhi, March 16, IRNA -- The bacteria, highly resistant to ultra-violet radiation, are not found elsewhere on Earth, leading to speculation on whether they are extra-terrestrial in origin.

According to IANS report, the Indian Space Research Organization (ISRO) in Bangalore announced Monday that the bacteria had been found in the upper stratosphere.

"All the three newly identified species had significantly higher UV resistance compared to their nearest phylogenetic neighbors. One of the three, identified as a member of the genus Janibacter, has been named Janibacter hoylei, the second Bacillus isronensis, and the third Bacillus aryabhata," ISRO said in a release.

"While the present study does not conclusively establish the extra-terrestrial origin of microorganisms, it does provide positive encouragement to continue the work in our quest to explore the origin of life," it said, adding: "The precautionary measures and controls operating in this experiment inspire confidence that these species were picked up in the stratosphere."

Janibacter hoylei is named after the distinguished Astrophysicist Fred Hoyle, Bacillus isronensis in recognition of ISRO's contribution in the balloon experiments which led to its discovery and Bacillus aryabhata after India's celebrated ancient astronomer Aryabhata. Indiaâ€™s first satellite was also named after Aryabhata.

The release said the experiment was conducted using a 26.7 million cubic feet balloon carrying a 459 kg scientific payload soaked in 38 kg of liquid neon.

The balloon was flown from the National Balloon Facility in Hyderabad, operated by the Tata Institute of Fundamental Research (TIFR). The release did not give the date when the balloon was flown.

"The payload consisted of a cryosampler containing 16 evacuated and sterilised stainless steel probes. Throughout the flight, the probes remained immersed in liquid neon to create a cryopump effect. These cylinders, after collecting air samples from different heights ranging from 20 km to 41 km, were parachuted down and safely retrieved.

"These samples were analyzed by scientists at the Center for Cellular and Molecular Biology, Hyderabad as well as the National Center for Cell Science (NCCS), Pune for independent examination, ensuring that both laboratories followed similar protocols to achieve homogeneity of procedure and interpretation," it said.

The experiment detected 12 bacterial and six fungal colonies, nine of which showed greater than 98 percent similarity with known species on Earth. "Three bacterial colonies were, however, totally new species," the release said.

Jayant Narlikar from the Inter-University Center for Astronomy and Astrophysics, Pune was the principal investigator and scientists U.R. Rao from ISRO and P.M. Bhargava from Anveshna supported as mentors of the experiment, the release said.

"This was the second such experiment conducted by ISRO, the first one being in 2001. Even though the first experiment had yielded positive results, it was decided to repeat the experiment by exercising extra care to ensure that it was totally free from any terrestrial contamination," ISRO said.